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I managed to resolve a couple of issues with tuning the debian ip network stack today.

1. ip_conntrack_tcp_timeout_established - I have been setting this value to 86400 (1 day in seconds) instead of the default 432000 (5 days in seconds) via sysctl.conf. The problem is that debian loads the sysctl.conf values before the network is loaded (procps.sh runs at 30, networking and shorewall at 40). So for now, not wanting to risk breaking anything that might need that script to run at 30 I just run it again at 41.
2. tcp_wmem & tcp_rmem - After doing research on tcp_window_scaling on Debian I ran across a number of people having problems because of the default debian values for these parameters beginning with kernel 2.6.17 and still the default with 2.6.18-4.  People recommended the following values (the old debian defaults and current ubuntu defaults):

net.ipv4.tcp_wmem = 4096 16384 131072
net.ipv4.tcp_rmem = 4096 87380 174760

Some links:

• http://inodes.org/blog/2006/09/06/tcp-window-scaling-and-kernel-2617/
• http://www.linuxquestions.org/questions/showthread.php?s=7056e2e24c24041152d23848487819c6&t=514191
• http://www.nohrsc.nws.gov/ (as described in the post linked above, this website will not load on machines with the current default debian settings)
• http://lists.debian.org/debian-kernel/2007/01/msg00662.html

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"Debian ip stack tuning" was written on March 16, 2007 and filed in all, debian